The present invention relates to a calibration method and apparatus, and more particularly, to a calibration method and apparatus which are capable of estimating installation angles of cameras mounted on a vehicle based on lanes.
An around view monitoring (AVM) system refers to a system that combines around images acquired from front, rear, left and right cameras of a vehicle into one image and provides the image such that a driver can recognize the surrounding situations. The AVM system has been spread as a driving support system for assisting a driver by providing a convenience to the driver. For example, the AVM system may provide a blind spot image of the vehicle or a rear view image of the vehicle during parking.
In order to combine images acquired from the plurality of cameras mounted in the vehicle into one image, internal parameters and external parameters of the cameras must be provided. The internal parameter may include an optical center and focal distance, and the external parameter may include an installation position and installation angle. Since the internal parameters are constant, values acquired through calibration can be continuously utilized as the internal parameters. However, since the external parameters can be easily changed by an external shock, the external parameters need to be continuously calibrated. Among the external parameters, the installation position is not significantly changed due to an installation jig, even though a camera is replaced. However, the installation angle is sensitive to an influence of disturbance, and an error of the installation angle may cause a problem that images acquired from the respective cameras are not combined.
In the related art, a skilled worker has performed calibration on cameras using a separate device in a calibration site having a specific calibration pattern drawn on the ground. Such a method can provide an accurate result because the worker can accurately know the relative position of a specific marker on the calibration pattern in advance. However, the method has a spatial limit in that a space having a predetermined area or more is required. For example, the space may be installed in a factory from which vehicles are shipped. Furthermore, since the method is performed by a skilled worker using a separate device, the time and cost of a driver are inevitably consumed. Therefore, there is a demand for a system capable of improving the convenience of a calibration operation.
The related art is disclosed in Korean Patent Publication No. 10-2011-0055421 published on May 25, 2011.